This article presents the results of a study testing the efficacy of an instructional model that attends to the science, literacy, and language learning needs of English Learners (ELs) through a curriculum development project. The model is based on the premise that reading, writing, and discourse are better served when these important language processes are regarded as a means to rich subject matter learning. The quasi-experimental study included fourth and fifth grade ELs who experienced a science curriculum in one of two conditions: (a) science, literacy, and language integrated curriculum; or (b) a content-comparable curriculum where the focus was "hands-on" science. ELs in the treatment condition outperformed ELs in the comparison group in science understanding and science vocabulary, but no statistically significant differences were found with science reading.